CN112009619A

CN112009619A - Tuning particle damping type floating raft

Info

Publication number: CN112009619A
Application number: CN202010918163.3A
Authority: CN
Inventors: 尹礼航; 张源潮; 刘松; 胡泽超; 邱元燃; 李创; 成建伟
Original assignee: Naval University of Engineering PLA
Current assignee: Naval University of Engineering PLA
Priority date: 2020-09-03
Filing date: 2020-09-03
Publication date: 2020-12-01
Anticipated expiration: 2040-09-03
Also published as: CN112009619B

Abstract

The invention relates to a tuned particle damping type floating raft, which solves the problems that the existing floating raft is poor in damping effect, needs to be matched with a vibration isolator for use, and needs to be further improved in low-frequency damping performance. The technical scheme comprises at least two layers of panels and rib plates for connecting the two adjacent layers of panels, and is characterized by also comprising a plurality of horizontally arranged tuning particle dampers positioned between the two adjacent layers of panels; the tuned particle damper is a cylinder, and the bottom surface of the tuned particle damper is fixed on the side wall of the ribbed plate. The floating raft vibration isolation structure is extremely simple, easy to install, free of changing the main body structure of the floating raft, capable of effectively improving the self vibration attenuation capacity of the floating raft, good in low-frequency vibration isolation effect and capable of being used independently or in cooperation with a vibration isolator.

Description

Tuning particle damping type floating raft

Technical Field

The invention relates to a floating raft vibration isolation device in the field of ships, in particular to a tuning particle damping type floating raft.

Background

The floating raft vibration isolation device is widely applied to vibration and noise reduction of large ships, the upper mechanical equipment is numerous, and the vibration excitation frequency characteristic is complex. Because the raft frame is large in size, the weight of the raft frame is limited by the ship as a whole, and the raft frame cannot be too large, the elastic modal frequency of the raft frame can be as low as the excitation frequency of mechanical equipment, and low-frequency resonance can be caused. Therefore, in the past, the raft frame is mainly designed by optimizing the structure of the raft frame, so that the elastic modal frequency of the raft frame avoids the excitation frequency of mechanical equipment, the raft frame cannot effectively attenuate vibration, and the vibration reduction and noise reduction of the floating raft vibration isolation device mainly depend on high-performance vibration isolators installed on the lower part of the floating raft vibration isolation device, such as an air bag vibration isolator, a rubber vibration isolator and the like, but the low-frequency vibration reduction effect is often poor.

For example, patent CN109695657A discloses a topology-optimized buoyant raft body structure, which comprises an upper panel, a lower panel, joint reinforcing ribs, middle longitudinal reinforcing ribs, middle transverse reinforcing ribs, two side longitudinal reinforcing ribs, two side transverse reinforcing ribs, self-locking joint holes and bolt holes. This technical scheme adopts topological structure to optimize the buoyant raft vibration isolation system, makes raft body structure under the unchangeable condition basically of performance, and the quality reduces about 60% for the cube structure, has strengthened raft body resistance to destruction ability simultaneously, makes it have great intensity. However, the raft body structure of the floating raft still has the following problems: (1) all the structures are rigidly connected, vibration damping cannot be independently realized, and the purpose of improving the vibration damping effect can be achieved only by matching with the air spring installed at the lower end. (2) The raft body structure of the floating raft is still partially changed, so that the area of the floating raft for mounting the vibration isolation device is reduced; (3) although it is described that the vibration isolation performance can be improved, the improvement effect is still unclear due to the lack of experimental data, and the low-frequency vibration isolation effect is not good due to the rigid connection of the raft structures.

Disclosure of Invention

The invention aims to solve the technical problems and provides a tuned particle damping type floating raft which is extremely simple in structure, easy to install, good in low-frequency vibration isolation effect and capable of being used independently or in cooperation with a vibration isolator, and the main body structure of the floating raft is not changed, and the self vibration attenuation capability of the floating raft can be effectively improved.

The technical scheme comprises at least two layers of panels, rib plates connecting the two adjacent layers of panels, and a plurality of horizontally arranged tuned particle dampers positioned between the two adjacent layers of panels; the tuned particle damper is a cylinder, and the bottom surface of the tuned particle damper is fixed on the side wall of the ribbed plate.

The tuned particle dampers are periodically arranged between two adjacent layers of the panel, and the whole structure presents symmetry and periodicity.

The tuning particle damper comprises a cylindrical shell and damping particles filled in the shell, wherein the filling rate of the damping particles is 100%, the diameter d is 1-10 mm, and the damping particles are graded or non-graded.

The damping particles are made of iron-based particles, black-based particles or lead particles, and the coefficient of restitution e of the damping particles is 0.1-0.9.

The radius of the bottom surface of the shell is 1/3-1/2 h, the height of the bottom surface of the shell is 100-400 mm, and the thickness of the shell is 2-6 mm.

In view of the problems in the background art, the inventor considers that the existing raft body structure with two or more layers is utilized, a plurality of horizontally arranged tuned particle dampers are arranged between two adjacent layers of plates, and the horizontal arrangement of the tuned particle dampers has the following considerations: (1) the tuned particle damper is arranged on the side wall of the ribbed plate, so that the overall damping effect is achieved, vibration energy is fully converted into heat energy to be dissipated, and the installation space of equipment is not occupied while vibration is reduced; (2) the tuning particle dampers are cylinders, and the distance between two adjacent layers of panels can be reduced to the greatest extent under the horizontal arrangement, so that the volume of the raft frame is reduced, the structure of the floating raft is more compact, and the strength is ensured; (3) the tuned particle dampers are horizontally arranged, and the bottom surfaces of the tuned particle dampers are directly arranged on the rib plates, so that the tuned particle dampers are not required to be installed on a panel by punching, the integrity of the panel is not damaged, and the thickness of the panel is not required to be increased; the vibration reduction capability, particularly the low-frequency vibration isolation effect, can be effectively improved on the premise of not increasing the volume and the mass of the structural body of the buoyant raft.

The tuned particle dampers are horizontally arranged on the side walls of the rib plates between two adjacent deck plates, and a plurality of tuned particle dampers are symmetrically and periodically arranged according to actual vibration reduction requirements, so that a lower-frequency band gap can be realized, vibration energy can be effectively absorbed, and a good low-frequency vibration reduction effect can be obtained; preferably, the radius of the bottom surface of the damper shell is 1/3-1/2 h, the height of the bottom surface of the damper shell is 100-400 mm, and the thickness of the shell is 2-6 mm. The concrete size can be reasonably selected according to the actual vibration reduction requirement, and the floating raft structure with the multilayer panels is flexibly suitable for use.

Through analysis and calculation, the structure of the invention has excellent medium and low frequency vibration reduction characteristics and extremely wide band gap characteristics, can be independently used when being applied to a floating raft vibration isolation system of large-scale mechanical equipment of ships, or can obtain double vibration reduction capability by matching with a high-performance vibration isolator, greatly attenuates the vibration transmission of the mechanical equipment, and has wide application prospect.

Drawings

Fig. 1 is a schematic view of the structure of a tuned particle-damped raft according to the present invention.

Figure 2 is a cross-sectional view of a harmonic particle damped buoyant raft structure.

Fig. 3 is a diagram of a model raft without tuned particle dampers.

Fig. 4 is a schematic diagram of a tuned particle-damped raft in accordance with the present invention.

Fig. 5(a) to 5(f) are graphs comparing the vibration transmission loss damping effect at points #1 to #6, respectively.

Wherein, 1-tuning particle damper, 1.1-shell, 2-first panel, 3-second panel, 4.1-transverse rib plate, 4.2-longitudinal rib plate and 5-vibration isolator mounting plate.

Detailed Description

Referring to fig. 1 and 2, the tuned particle damping raft of the present invention includes at least two layers of panels, in this embodiment, two layers of panels are a first panel 2 and a second panel 3, two adjacent panels are vertically connected by a rib, the number and positions of the ribs are arranged according to actual requirements, in this embodiment, the ribs include transverse ribs 4.1 and longitudinal rib rows 4.2, a plurality of tuned particle dampers 1 horizontally arranged are periodically arranged between two adjacent panels, the bottom surfaces of the tuned particle dampers are fixed on the side walls of the ribs, and the whole structure presents symmetry and periodicity. The tuned particle damper 1 comprises a cylindrical shell 1.1 and damping particles filled in the shell 1.1, wherein the radius of the bottom surface of the shell 1.1 is 1/3-1/2 h, the height of the bottom surface of the shell is 100-400 mm (the specific height is designed according to actual requirements), the thickness of the shell 1.1 is 2-6 mm, the filling rate of the damping particles is 100%, the filling mode is natural accumulation, the diameter d is 1-10 mm, preferably 2-4 mm, grading or non-grading is adopted, the damping particles are made of iron-based particles, black-based particles or lead particles, and the coefficient of restitution e is 0.1-0.9.

While only a two-ply panel construction is shown in fig. 1 and 2, the raft may also have a multi-ply panel construction with multiple tuned particle dampers horizontally disposed between adjacent panels, as desired.

Further, the buoyant raft can be matched with the vibration isolator for use through the vibration isolator mounting plate 5 according to requirements.

To further verify the damping effect of the present invention, the following analytical calculations were performed:

the vibration transmission loss of the raft structure shown in fig. 3 without the tuned particle damper 1 installed and the vibration transmission loss of the raft structure of the present invention shown in fig. 4 with the tuned particle damper 1 installed were measured, respectively.

In order to simulate motor excitation, an excitation source in the model adopts central four-point simultaneous excitation; the output integration points are selected from points #1 to #6, which are located on the upper surface of the airbag installation, and the boundary condition is a free boundary condition, see fig. 3.

And (3) analysis results: referring to fig. 5(a) -5 (f), comparison graphs of vibration transmission loss damping effect of points #1 to #6 are shown, wherein the dotted line represents vibration transmission loss of the raft structure without the tuned particle damper 1 installed, and the solid line represents vibration transmission loss of the raft structure with the tuned particle damper 1 installed.

It can be seen from the graph that the damping effect is different at different positions, and the 6 points can obtain better damping effect in the middle and low frequency full frequency bands, wherein the low frequency vibration isolation effect of the #4 point and the #5 point is good, and a plurality of line spectrums are eliminated; the structure in which the plurality of tuned particle dampers 1 are periodically arranged exhibits a band gap characteristic, and a band gap of a lower frequency can be realized.

Analysis results show that the tuned particle damping type floating raft has vibration damping effects in middle and low frequency full frequency bands under the condition of single use, and has excellent low-frequency vibration isolation effects in partial positions, so that the vibration damping capacity of a floating raft vibration isolation system is greatly improved, and therefore, the tuned particle damping type floating raft can further have better double vibration damping capacity under the condition of being matched with vibration isolation devices such as a rubber vibration isolator or an air bag vibration isolator.

Claims

1. A tuned particle damping type buoyant raft comprises at least two layers of panels and rib plates connecting the two adjacent layers of panels, and is characterized by also comprising a plurality of tuned particle dampers which are positioned between the two adjacent layers of panels and are horizontally arranged; the tuned particle damper is a cylinder, and the bottom surface of the tuned particle damper is fixed on the side wall of the ribbed plate.

2. The tuned particle damped raft as recited in claim 1 wherein said tuned particle dampers are periodically disposed between adjacent two of said panels, said configuration exhibiting symmetry and periodicity throughout.

3. The tuned particle damped raft as set forth in claim 1 or 2, wherein said tuned particle damper comprises a cylindrical hull and damping particles filled in said hull, said damping particles having a fill rate of 100% and a diameter d of 1-10 mm, graded or non-graded.

4. The tuned particle damped raft of claim 1 or 2, wherein said damping particles are iron-based particles, ubbased particles, or lead particles, and have a coefficient of restitution e of 0.1 to 0.9.

5. The tuned particle damped raft as set forth in claim 3, wherein said cylindrical hull has a bottom radius r of 1/3-1/2 h, a height h of 100-400 mm, and a hull thickness of 2-6 mm.